Abdomen:Visceral arteries:Renals
Renal Arteries * Kidney is supplied by 1 renal artery in most individuals ** Renal artery usually 5-6 mm in diameter, 4-6 cm long ** 30-40% incidence of multiple renal arteries *** More common on right side if present * Renal arteries arise from abdominal aorta at L2 level ** Right renal artery arises anterolaterally from aorta *** Slightly longer than left renal artery *** Courses posterior to both inferior vena cava (IVC) and right renal vein ** Left renal artery arises laterally from aorta *** Courses posterior to corresponding renal vein ** Main renal arteries divide at renal hilum into anterior and posterior segmental arteries * Intrarenal Arterial Anatomy ** Anterior segmental artery supplies upper, middle, and lower segments of kidney *** Usually also supplies apical segment ** Posterior segmental artery usually supplies only posterior segment of kidney *** May supply apical segment in minority of patients ** Segmental arteries yield interlobar arteries *** Course alongside renal pyramids toward periphery *** Yield arcuate arteries at corticomedullary junction **** Arcuate arteries travel across top of renal pyramids and give rise to interlobular arteries **** Interlobular arteries are tiny parenchymal branches that course toward kidney surface and subdivide into afferent glomerular arterioles Branches of Renal Arteries * Inferior adrenal artery ** Arises superiorly from proximal main renal artery *** Supplies inferior aspect of adrenal gland *** Adrenal gland is also supplied by superior adrenal artery (abdo aorta) and middle adrenal artery (inferior phrenic artery) * Superior capsular artery ** Arises adjacent to, or with, inferior adrenal artery ** Primarily supplies perirenal (capsular) fat ** May anastomose with retroperitoneal arterial plexus *** Plexus is derived from several tiny aortic branches ** Communicates with intrarenal arteries via perforating branches * Middle capsular artery ** Arises from main renal artery or its branches *** Medial course toward renal sinus; gives off branches that supply ventral and dorsal perirenal fat *** Perforating middle capsular arteries arise from renal interlobular arteries, penetrate capsule, and anastomose with perirenal branches * Inferior capsular artery ** Commonly arises from gonadal artery ** When present, anastomoses with superior capsular artery; forms arcade along lateral margin of kidney *** Arcade communicates with perforating capsular arteries and other retroperitoneal arteries * Capsular arteries may provide collateral flow to kidney ** Occurs with severe renal artery stenosis/occlusion located distal to capsular artery origin ** Exophytic renal neoplasms may derive portion of arterial supply from these vessels *** e.g., angiomyolipoma, renal cell carcinoma * Ureteric arteries ** Superior ureter is supplied by branches arising from renal, inferior adrenal, or testicular artery ** Distal ureter is supplied by tiny branches from common, internal, and external iliac arteries ** May provide collateral flow to kidneys in presence of renal artery stenosis/occlusion *** Enlarged collaterals may cause "ureteral notching" Variant Renal Arterial Anatomy * 30-40% incidence of variations in number, location, and branching patterns of renal arteries ** Accessory renal arteries usually arise from aorta *** May arise from common iliac arteries *** Rarely arise above superior mesenteric artery (SMA) * Horseshoe kidneys always have multiple renal arteries ** Fused portion of horseshoe kidney (isthmus) may be supplied by distal aorta and iliac arteries * Other congenital variations in renal configuration/position (e.g., pelvic kidney, crossed fused ectopia) have high incidence of variant arterial anatomy